Spectrometer, Grating, Fiber Optic
Wednesday, September 20, 2006
A Grating Fiber Optic Spectrometer has been designed and developed with a light and dark diffraction pattern embossed directly on the Fiber Optic by a laser. The Laser has an output wavelength corresponding to an absorption band of the Fiber Optic (germanium-doped).
The diffraction pattern modifies the Fiber Optic core by changing the index of refraction in the dark bands. The spacing between the light lines and the dark lines is the Grating period. The embossing procedure requires the removal of the Fiber Optic coating, exposing the core to a high-energy laser, and then recoating the Fiber Optic. Recoating does not restore the original mechanical intensity of the Fiber Optic. The Laser embossed grating of the Fiber Optic results in an optical filter with a wavelength range of 400 nm to 2000 nm and a bandwidth of 0.1 nm at 1300 nm.
The Spectrometer requires a broadband light source coupled to the Fiber Optic. The Grating reflects or filters out the wavelength determined by the Grating spacing. The Grating spacing is changed when used as a strain gauge, resulting in different wavelengths being reflected.
Source: “Measuring with Light” (in four parts) by Peter L. Fuhr, Sensors Magazine, April-July 2000; Peter L. Fuhr, San Jose State University, San Jose, CA
Reference: “Fundamental of fiber optic sensing: technique, applications and more applications”, by Peter L. Fuhr, Sensor Expo Conference Program, Anaheim, CA, May 2000
Industrial Products
posted by JD52 @ 8:35 PM,
